MakeLists.txt: Build aktuakizr_info if -DBUILD_OSTREE=ON
MakeLists.txt: Build aktuakizr_info if -DBUILD_OSTREE=ON

Build executable aktuakizr_info only if BUILD_OSTREE
is enabled. Otherwise building of aktuakizr_info
will fail due to  error: "‘class FSStorage’ has
no member named ‘loadMetadata’".

Signed-off-by: Leon Anavi <15d13d7e2c6115f28df053122512bfcb5eb2dbf7@konsulko.com>

advancedtelematic/aktualizr,advancedtelematic/sota_client_cpp,advancedtelematic/aktualizr,advancedtelematic/aktualizr,advancedtelematic/aktualizr,advancedtelematic/sota_client_cpp